The correct answer is option 3 - Plants. Primary producers are the organisms that can make their own food through photosynthesis. Plants are the main primary producers in most ecosystems because they have chlorophyll, which allows them to capture sunlight and convert it into energy through photosynthesis. This process creates organic compounds that serve as food sources for other organisms in the ecosystem. Option 1 and 2 (Women and Men) are incorrect because primary production is not related to gender but to the ability to produce food. Option 4 (Bacteria) is incorrect because while some bacteria can perform photosynthesis, they are not the primary producers in most ecosystems.